What would be the proper method to connect two separate Ademco 748 sirens to the same GC3 panel.

I am assuming that I would need a relay and possibly an external power source of some sort to make it work properly and not damage the panel.

Can someone recommend the relay (and power source if needed) that would work with the GC3 panel alarm/siren output?

As an aside, it's an Archive building, and we've been advised by the police dept to put as much external alarm noise as possible out. Our backside faces onto a cemetery and is quite vulnerable, and has been broken into a few times. We are on a corner and the police recommended sirens pointing out towards both streets.

Thanks for any help you can give!